Advances in electronic devices generally include reducing the size of components that form integrated circuits. With smaller circuit components, the value of each unit area on a semiconductor wafer becomes higher, because the ability to use all of the wafer area for circuit components improves. To properly form an integrated circuit using advanced circuit designs that use much higher percentage of the wafer area for smaller components, it is critical that particle counts on the semiconductor wafer be reduced below levels which were previously acceptable for many circuit designs. For example, minute particles of less than 0.2 microns are unacceptable for many of the popular advanced circuit designs, because they can damage the integrated circuit by shorting out two or more lines. In order to clean a semiconductor wafer and remove unwanted particles, a process known as chemical mechanical polishing (CMP) has become popular.
CMP systems coat the semiconductor wafer with a slurry that serves to not only lubricate mechanical devices that contact and polish the semiconductor wafer, but also to provide a delicately abrasive compound that polishes the semiconductor wafer. After polishing the semiconductor wafer, the CMP system attempts to rinse the slurry from the wafer and then transfers the wafer to a buffing station. At the buffing station, an attempt is made to reduce the particle count further by buffing the semiconductor wafer circuit. Thereafter, the CMP system rinses the semiconductor wafer. Then, the CMP system releases the wafer for further processing.
Certain limitations relate to the process that known CMP systems use. One limitation is the time required to polish the semiconductor wafer. Any improved method that reduces the processing time would improve the overall throughput or the manufacture of electronic devices. Another limitation relates to the handling of the semiconductor wafer in the polishing process. Oftentimes, scratches occur on the semiconductor wafer surface due to the wafer handling. If there were a way to limit the amount of handling of the semiconductor wafer, much of this scratching could be avoided. A further and very important problem associated with current CMP systems is that the slurry that the process uses often forms particles on the semiconductor wafer. These particles, just like impurities from other parts of the fabrication process, can detrimentally affect operation of the resulting integrated circuit.